DE3730885A1 - Fuel for Otto engines (spark ignition engines) - Google Patents

Abstract

The invention relates to fuels for Otto engines, containing small amounts of copolymers of olefins having from 2 to 40 carbon atoms and maleic anhydride and/or cycloolefins and maleic anhydride having a total molecular mass of from 500 to 20,000 g per mole, with the carboxyl groups of the copolymers being partially reacted with alkali or alkaline earth metal compound to form the alkali metal or alkaline earth metal salts and the remainder of the carboxyl groups being reacted with alcohols and/or amines having up to 50 carbon atoms to form the corresponding ester and/or amide groups and/or amonium salts.

Description

The invention relates to fuels for gasoline engines containing Copolymers of olefins or cycloolefins and maleic anhydride, where the carboxyl groups of the copolymers partly in the form of the alkali metal or alkaline earth metal salts and the rest of the carboxyl groups in the form of ester and / or amide groups and / or ammonium salt groups.

From DE-OS 36 20 651 is known for the prevention or reduction of Signs of wear on the exhaust valves or valve seats of Gasoline engines, small amounts of alkali metal or fuels Alkaline earth metal salts of certain derivatives of succinic acid to add. However, the compounds have the disadvantage that they are in the Otto engines do not reduce corrosion.

It was therefore the task to find substances that are in addition to prevention or reduction of wear and tear on the valves of gasoline engines at the same time reduce the corrosion in the gasoline engines.

It has now surprisingly been found that this problem is solved with fuels for gasoline engines, containing small amounts of copolymers from olefins with 2 to 40 carbon atoms and maleic anhydride and / or Cycloolefins and maleic anhydride with a total molecular weight of 500 to 20,000 g per mole, the carboxyl groups of the copolymers partially with alkali or alkaline earth to form the alkali metal or Alkaline earth metal salts are implemented and the rest of the carboxyl groups with Alcohols and / or amines with up to 50 carbon atoms to the corresponding Ester and / or amide groups and / or ammonium salts is implemented.

The new fuel additives have the advantage of being effective common gasoline additives in gasoline engines and at the same time the appearance of wear on the valves prevent or at least greatly reduce and further surprisingly considerably reduce the occurrence of corrosion in the gasoline engines or even prevent.

The fuel additives according to the invention are expediently produced in two process stages. The first stage of the process is the preparation of the copolymers from the olefins having 2 to 40 carbon atoms and maleic anhydride or cycloolefins and maleic anhydride. In the second process stage, the olefin / maleic anhydride copolymers or cycloolefin / maleic anhydride copolymers obtained are reacted with alcohols and / or amines and the salts of the alkali and alkaline earth metals are formed. In order to achieve the required solubility of the fuel additives, it is appropriate to use longer-chain alcohols and / or amines in the preparation of the copolymers from olefins with a small number of carbon atoms in the second process stage and / or, if appropriate, the proportion of the carboxyl groups which are associated with the alcohols and / or to implement amines, increase. Correspondingly, when using olefins with a higher number of carbon atoms, ie with correspondingly longer alkyl chains, alcohols and / or amines with shorter alkyl chains or the proportion of carboxyl groups associated with the To lower alcohols and / or amines.

* Commercial products from Gulf Oil Chemical Company, USA

Straight-chain and / or branched olefins and / or cycloolefins having 2 to 40 carbon atoms, preferably 4 to 30 carbon atoms, are used for the production of the alternating copolymers from olefins or cycloolefins and maleic anhydride. Of the olefins, those in which the double bond is in the 1-position are particularly suitable. Examples of olefins are: ethene, propene, n-butene-1, isobutene-1, n-pentene-1, 3-methylbutene-1, n-hexene-1, 4-methylpentene-1, 3,3-dimethylbutene- 1, n-heptene-1, 4-methylhexene-1, n-heptene-1, 5-methylhexene-1, 4,4-dimethylpentene-1, n-octene-1, 2,4,4-trimethylpentene-1, 2,4,4-trimethylpentene-2, diisobutene (isomer mixture of approx. 80% 2,4,4-trimethylpentene-1 and approx. 20% 2,4,4-trimethylpentene-2), 4,4-dimethylhexene-1 , Decen-1 (Gulftene 10 *), Dodecen-1 (Gulftene 12 *), Tetradecen-1 (Gulftene 14 *), Hexadecen-1 (Gulftene 16 *), Oktadecen-1 (Gulftene 18 *), C₂₀-Olefin-1, C₂₂-Olefin-1 , C₂₄-olefin-1, C₂₀-C₂₄-olefin-1 fraction (Gulftene 20-24 *), C₂₆-olefin-1, C₂₈-olefin-1, C₂₄-C₂₈-olefin-1 fraction (Gulftene 24-28 *), C₃₀-olefin-1 (Gulftene 30 + *), C₄₀-olefin-1 and mixtures with each other. Suitable cycloolefins generally have 4 to 16 carbon atoms, preferably 4 to 12, in particular 4 to 8 carbon atoms. Examples include cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene.

As the comonomer maleic anhydride, the usual commercially available Find quality use. However, it is also possible Maleic anhydride to use that up to 20% other olefinic unsaturated dicarboxylic acid anhydrides such as itaconic acid, Contains glutaconic, methylene maleic, citraconic anhydride.

The alternating copolymers have molar masses of 500 to 20,000 g / mol, preferably 800 to 10,000 g / mol.  

The production takes place according to known conventional polymerization processes such as bulk, suspension, precipitation and solution polymerization and Initiation with conventional radical donors such as acetylcyclo hexanesulfonyl peroxide, diacetyl peroxidicarbonate, dicyclohexyl peroxidicarbonate, Di-2-ethylhexyl peroxidicarbonate, tert-butyl perneodecanoate, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), tert-butyl perpivalate, tert-Butylper-2-ethyl-hexanoate, tert-butyl permaleinate, 2,2′Azobis (iso butyronitrile), bis (tert-butyl peroxide) cyclohexane, tert-butyl peroxy isopropyl carbonate, tert-butyl peracetate, dicumyl peroxide, Di-tert-amyl peroxide, di-tert-butyl peroxide, p-methane hydroperoxide, Cumene hydroperoxide and tert-butyl hydroperoxide and mixtures among themselves. These initiators are usually used in amounts of 0.1 to 10 wt .-%, preferably 0.2 to 5 wt .-%, calculated on the monomers Cycloolefin or olefin + maleic anhydride used.

The copolymerization usually takes place at temperatures from 40 to 250 ° C, preferably 80 to 220 ° C, with when using olefins with Boiling temperatures below the polymerization temperature expediently below Pressure is being worked on. The polymerization is expediently in the absence of air, d. i.e. if it is not possible to work under boiling conditions, carried out under inerting agents such as nitrogen, since Atmospheric oxygen delays the polymerization. By using Redox coinitiators such as benzoin, dimethylaniline, Ascorbic acid and organically soluble complexes of heavy metals such as Copper, cobalt, manganese, iron, nickel and chromium can cause the reaction be accelerated. The amounts usually used are 0.1 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight. When choosing the Initiator or the initiator system, it is expedient in the chosen Polymerization temperature to ensure that the half-life of Initiator or the initiator system is less than 3 hours. At 150 ° C for example, the half-life of tert-butyl hydroperoxide is less than 3 hours. The initiator system 1% by weight of tert-butyl hydroperoxide / 5% by weight Copper II acetylacetonate, on the other hand, already has a comparable one at 100 ° C Polymerization behavior as 1% by weight of tert-butyl hydroperoxide 150 ° C. For example, is polymerized at a low temperature and Polymerized out at a higher temperature, usually with 2 or more Initiators worked.

It is often useful to achieve low molecular weight copolymers in To work in the presence of regulators. Suitable regulators are, for example Allyl alcohols, organic mercapto compounds such as 2-mercaptoethanol, 2-mercaptopropanol, mercaptoacetic acid, mercaptopropionic acid, tert-butyl mercaptan, n-butyl mercaptan, n-octyl mercaptan, n-dodecyl  mercaptan and tert-dodecyl mercaptan, which are generally in amounts of 0.1 wt .-% to 10 wt .-% are used.

The initiators, co-initiators, regulators and polymerization temperatures mentioned can be used equally for all polymerization methods. Suitable apparatus for the polymerization are e.g. B. usual Mixing kettle with, for example, anchor, blade, impeller or multi-stage impulse counterflow stirrer.

The simplest method of polymerization is bulk polymerization. Here the olefin and the maleic anhydride in a molar ratio Polymerized in the presence of an initiator and in the absence of solvents. This process is particularly suitable for such copolymers, in which the olefin used has 8 or more carbon atoms. Conveniently you put the olefin or cycloolefin or a mixture various olefins and / or cycloolefins in the reactor, heated under Stir to the desired polymerization temperature and meter that Maleic anhydride, the initiator and optionally coinitiator and Regulator evenly within 1 to 10 hours, preferably 2 to 5 hours. It is expedient to separate the initiator and the coinitiator into Form of solutions in the olefin or cycloolefin to be copolymerized meter in. The maleic anhydride is easily in the form of e.g. B. 70 ° C heated melt. Sometimes it’s an advantage Excess olefin, e.g. B. 10% excess to use the Completely polymerize maleic anhydride. The excess olefin or cycloolefin can then by distillation, preferably under vacuum, be removed from the copolymer melt. The copolymer can be then directly to the fuel additive according to the invention in the melt or react even after dilution with a suitable solvent.

Other methods for the simple production of copolymers of malein Acid anhydride with olefins or cycloolefins are the precipitation and Suspension polymerization. In the case of precipitation polymerization, such Solvents used in which the monomers olefin or cycloolefin and maleic anhydride, soluble and the copolymer formed insoluble is and fails. Such solvents are, for example, aromatic Hydrocarbons such as benzene, toluene, o-xylene, m-xylene, p-xylene and the technical xylene mixtures, ethylbenzene, cumene and hydrogen halide such as methylene chloride, 1,1- and 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichlorethylene, 1,1,2-trichloroethane, perchlorethylene, 1,2-dichloropropane, butyl chloride, 1,1,2-trichloro-1,2,2-trifluoroethane, 1,1,1,2-tetrachloro-2,2-difluoroethane, 1,1,2,2-tetrachloro-1,2-difluoroethane and ethers such as diethyl ether, dipropyl ether, dibutyl ether, methyl tert-butyl ether, Diethylene glycol dimethyl ether and mixtures with one another. At  the suspension polymerization, such solvents are used in which all or at least one of the monomers and the formed Polymers are insoluble. Straight-chain and are suitable for this branched aliphatic and cycloaliphatic hydrocarbons. Pentane, hexane, heptane, octane, Isooctane, cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, Diethylcyclohexane and mixtures with each other. In the It is expedient to carry out the precipitation polymerization, especially if working at concentrations above 40 wt .-%, and at Suspension polymerization is imperative in the presence of a Protective colloids work to prevent aggregation. As Protective colloids are suitable polymeric substances in the solvents are readily soluble and do not react with the monomers. Suitable are, for example, copolymers of maleic anhydride with vinyl alkyl ethers and / or olefins with 8 to 20 carbon atoms and their monoesters with C₁₀ to C₂₀ alcohols or mono- and diamides with C₁₀ to C₂₀ alkylamines as well as polyalkyl vinyl ethers whose alkyl group contains 1 to 20 carbon atoms, such as for example polymethyl, polyethyl, polyisobutyl and polyocta decyl vinyl ether. The added amounts of protective colloid are usually 0.05 to 4% by weight (calculated on the monomers used), preferably 0.1 to 2% by weight, it often being advantageous to have several Combine protective colloids. In the polymerization, it is advisable the solvent, the protective colloid and a monomer in the reactor submit and at selected polymerization temperature under intense Stir the comonomer and the initiator and optionally the Add the coinitiator and regulator. It is in general irrelevant whether the maleic anhydride is submitted and the olefins or cycloolefins are metered in, or whether the olefins or cycloolefins are presented and the maleic anhydride is metered in. of course is it is also possible to present only the solvent and the protective colloid and the monomers - olefin or cycloolefin + maleic anhydride - to dose together. The feed times for monomer and initiator are in generally between 1 and 10 hours, preferably 2 and 5 hours. It is also possible to polymerize all feed materials together in one reactor, however, problems with heat dissipation can occur, so that a such way of working is less appropriate. The concentrations of the too polymerizing monomers are between 20 and 80% by weight, preferably 30 up to 70% by weight. The polymer suspensions can be used directly in evaporators such as belt dryers, paddle dryers, spray dryers and Fluid bed dryers which isolate polymers. When working in suitable solvents that are added directly to fuels can, the further conversion to the alkali or alkaline earth metal salt and Ester and / or amide can be carried out directly in the suspension. The Precipitation and suspension polymerization is particularly suitable for  Preparation of copolymers from maleic anhydride and olefins with 2 up to about 10 carbon atoms. If olefins with a higher number of carbon atoms can be used, the case may already occur that the educated Copolymers are soluble in the solvent, so that the polymerization is already to be regarded as solvent polymerization, as follows is described in more detail.

Solution polymerization is carried out in solvents in which the monomers and the copolymers formed are soluble. It is for this suitable for all solvents that meet this requirement and that use the Monomers do not react. For example, these are acetone, Methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, ethyl acetate, Butyl acetate, tetrahydrofuran and dioxane, being used to achieve low molecular weight copolymers tetrahydrofuran and dioxane are particularly good are suitable. As with bulk, suspension and precipitation polymerization it is also expedient here, the solvent and a monomer component to submit and the second component with the initiator and, if necessary Add the co-initiator and controller. Solvents and Maleic anhydride placed in the polymerization reactor and after reaching the polymerization temperature then the olefin or cycloolefin and the Initiator and optionally coinitiator and regulator are added. However, it is cheaper to use solvents and olefins or cycloolefins to submit and the maleic anhydride and the initiator and, if appropriate the coinitiator and regulator at the chosen polymerization temperature meter in. This procedure provides less colored polymer solutions. The concentrations of the monomers to be polymerized are between 20 and 80% by weight, preferably 30 and 70% by weight. The solid copolymer can easily be isolated by evaporating the solvent. But here too it is advisable to choose a solvent in which the further conversion to the alkali or alkaline earth salt and with alcohols and / or amines can take place.

The copolymers of olefins or Cycloolefins and maleic anhydride then become the esters and / or amides and / or ammonium salts and to the alkali or Alkaline earth metal salts implemented.

For the implementation of the copolymers to the esters and / or amides Alcohols and / or amines with up to 50 carbon atoms are used.  

As a rule, amines of the general formula

used in which R¹ and R² are the same or different unsubstituted or substituted, optionally simply olefinically unsaturated Hydrocarbon radicals, which are generally 1 to 25, preferably Have 5 to 25 carbon atoms, or in which R¹ is H- and R² is one unsubstituted or substituted, optionally simply olefinic unsaturated hydrocarbon radical with generally 1 to 50, preferably 5 to 50, in particular 8 to 30 carbon atoms. Suitable Amines are e.g. B. Di-2-ethylhexylamine, dioleylamine. With a special advantage isotridecylamine and diisotridecylamine are used.

In general, alcohols having 1 to 50 carbon atoms, preferably 4 to 40 carbon atoms, in particular 5 to 30 carbon atoms, are used for the esterification of the copolymers of olefins or cycloolefins and maleic anhydride. With a sufficiently long α- olefin of the copolymer, polyhydric alcohols such as. B. neopentyl glycol or pentaerythritol advantageous.

Generally, the carboxyl groups of the copolymers become from olefins or cycloolefins and maleic anhydride at 5 to 80%, preferably 10 up to 70%, in particular 15 to 60%, of the amides and / or ammonium salts and / or esters implemented. The implementation of the copolymers from olefins or Cycloolefins and maleic anhydride with the amines and / or alcohols generally takes place in the melt or after dilution with a suitable solvent. Examples of suitable solvents are above for the preparation of the copolymers from olefins or Cycloolefins and maleic anhydride by precipitation, suspension and Solution polymerization solvent called into consideration. Preferably become aromatic, aliphatic or cycloaliphatic hydrocarbons used.

When reacting with the amines, temperatures of 20 up to 150 ° C, preferably 20 to 120 ° C, especially 30 to 100 ° C applied. The esterification with the alcohols usually takes place at Temperatures from 20 to 200 ° C, preferably 80 to 200 ° C.  

This is how it is done, for example, when reacting with the amines before that the copolymer of olefins or cycloolefins and Maleic anhydride e.g. B. in a reaction vessel, for example in molten form or in a solvent, presented and with stirring at temperatures of 60 to 90 ° C the amine enters and under 1 to 2 hours Stirring. You usually get the half amide, where at excess amine the remaining carboxyl group as Alkyl ammonium salt is present.

The esterification of the copolymers can also be carried out in a corresponding manner Olefins or cycloolefins and maleic anhydride with the alcohols take place, the esterification thermally or by acidic catalysis, for. B. by phosphoric acid. You usually get Half esters, which as such or after partial amidation or Partial neutralization of the remaining carboxyl groups with amines for the can use further implementation of the alkali or alkaline earth salts.

The amides and / or esters and / or ammonium salts of the copolymers obtained of olefins or cycloolefins and maleic anhydride are used for Conversion of the remaining carboxyl groups into the alkali or Alkaline earth metal salts with a basic alkali metal or alkaline earth metal compound, e.g. B. the hydroxides, carbonates or alcoholates, implemented. For example, for the production of the potassium metal salts Solutions of the amides and / or esters and / or ammonium salts of the copolymers of olefins or cycloolefins and maleic anhydride with the calculated amount of potassium compound, e.g. B. a solution of KOH or KOCH₃ useful in alcohols, e.g. B. a C₁ to C₆ alcohol such as methanol, Ethanol, propanol, butanol, implemented. From the reaction mixture obtained the solvents and water formed are expedient in a vacuum deducted.

The fuel additives according to the invention are called alkaline earth metal salts or alkali metal salts are used, with alkali metal salts being preferred will. Suitable alkaline earth metal salts are e.g. B. the magnesium or Calcium salts. The alkali metal salts are the lithium, sodium, Potassium, rubidium, cesium salts into consideration, the potassium salts are preferably used. The proportion of alkali metal or alkaline earth metal in the fuel additives according to the invention, based on the Fuel addition in general at least 3 wt .-%, preferably 3 to 25% by weight, in particular 4 to 20% by weight, with particular advantage 4 to 15% by weight.  

The new fuel additives are used in petrol engines in the Usually in amounts of 10 to 2000 ppm by weight, preferably from 50 to 1000 ppm by weight added.

In addition to the alkali metal or Alkaline earth metal salts additionally known antioxidants Phenol or amine base included. In particular, it is advantageous Fuel additives for cleaning and keeping the intake system clean phenolic antioxidants to increase the storage stability of the Combine fuels.

As a good solvent or solubilizer for the above Components to be added to fuel have residual oils from the Oxo alcohol synthesis proven.

Oxo alcohol residues from the butanol, isobutanol, Pentanol, hexanol, heptanol, octanol, nonanol, decanol, Undecanol or dodecanol synthesis. This is particularly advantageous Use of oxo alcohol residues from butanol synthesis. Are next to it other solvents or solvent mixtures can also be used, the one homogeneous mixture of the components in the weight ratios mentioned above surrender. The effect of the gasoline additives according to the invention is not just limited to gasoline. It has been shown that you can can also be used in aviation fuels, especially in aviation fuels for Piston engines. Likewise, the compounds of the invention do not work only in carburetor engines, but also in engines with injection systems for the fuel.

The fuels provided with the new additive can still usual additives, e.g. B. octane-improving additives or oxygen-containing Components, e.g. B. methanol, ethanol or methyl tertiary butyl ether contain.

The following examples illustrate the invention.

In Examples 1 to 5, the copolymers are produced from Olefins and maleic anhydride are described.

The parts specified are parts by weight. The molecular weights were determined by Gel permeation chromatography determined using eluent Tetrahydrofuran and narrowly distributed fractions of polystyrene for calibration be used.

Example 1

980 parts were placed in a stainless steel pressure stirred kettle with a capacity of 5 l Maleic anhydride, 1440 parts technical xylene and 14 parts polyvinyl ether with a K value of 50 (measured 1% by weight in cyclohexanone at 25 ° C.), pressed three times with 3 bar nitrogen and heated to 140 ° C. Then 600 parts of isobutene and a solution within 3 hours from 46.2 parts of tert-butyl-2-perethylhexanoate and 30.8 parts of di-tert-butyl peroxide in 100 parts of xylene within 3.5 hours evenly in the The stirred kettle is metered in and then reheated for 1 hour. Subsequently was carefully released while distilling off xylene and towards the end the xylene distillation distilled off under vacuum. At 140 ° C the polymer formed as a melt. After cooling, the polymer lay as light brown, brittle resin, the molecular weight of which was 2500 g / mol.

Example 2

In a reactor as in Example 1, 1612.5 parts of diisobutene and 73.5 parts of maleic anhydride initially charged, three times with 3 bar of nitrogen pressed and heated to 160 ° C. Then within 3 hours 1396.5 parts of maleic anhydride and a solution of within 4 hours 150 parts of di-tert-butyl peroxide in 94.5 parts of diisobutene evenly added. The mixture was then reheated for 1 hour. Then was carefully relaxed and the excess diisobutene distilled off against End by applying vacuum. The molar copolymer was at 150 ° C Maleic anhydride and diisobutene as a melt. After freezing lay the copolymer as a brittle resin. The molar mass was 2040 g / mol.

Example 3

In a 4-liter glass flask, 1500 parts of octadecene-1 were placed and in weak nitrogen flow heated to 190 ° C. Now within 2 hours 588 g of maleic anhydride in liquid form and a solution of 21 parts Ditert.-butyl peroxide was added in 42.8 parts of octadecene-1. After that was reheated for 2 hours and the viscous polymer melt on a sheet emptied, solidifying into a brittle brownish resin. The Molar mass was 4800 g / mol.

Example 4

In a 4-liter glass flask, 1195 parts of a C₂₀-C₂₄-olefin-1 mixture (Gulftene C₂₀-C₂₄) in a weak nitrogen flow to 190 ° C heated and 392 parts of maleic anhydride and 16 parts of di-tert-butyl peroxide evenly metered in 4 hours and then 2 hours  reheated. The yellowish, viscous melt was then applied to a Sheet emptied, solidifying into a yellow, brittle resin. The Molar mass was 8900 g / mol.

Example 5

1671.4 parts of a C₃₀ olefin (Gulftene 30+) heated to 180 ° C in a weak nitrogen stream and within 4 hours. 392 parts maleic anhydride and 20.5 parts di-tert-butyl peroxide evenly dosed. Then it was reheated for a further 2 hours and the emptied viscous yellow melt onto a metal sheet, turning it into a yellow one brittle resin froze. The molar mass was 1600 g / mol.

Examples 6 to 10

The copolymers obtained in Examples 1 to 5 were prepared according to the Examples 6 to 11 in the fuel additives according to the invention transferred by first to the amines and / or alcohols corresponding amides and / or alcohols and then the corresponding Potassium salts were implemented.

For the conversion to the amides, the copolymers from the Examples 1 to 5 dissolved n-hexane or xylene and the amines Temperatures of 30 to 100 ° C to the copolymers with stirring given. The mixture was then stirred for a further 1 to 2 hours.

Accordingly, the esters were catalyzed by thermal or acid Implementation (addition of 0.1 wt .-% phosphoric acid) of the copolymers with the corresponding alcohols obtained at temperatures from 90 to 110 ° C. The The course of the amide and ester formation was monitored in the IR spectrum.

To produce the potassium salts, the amides or Esters of the copolymers containing reaction solutions with 20 wt .-% ethanolic KOH solution containing the calculated amount of KOH added and from the mixture obtained in vacuo at temperatures of 70 to 90 ° C. the solvents and the water formed are drawn off.

The details of the reaction conditions in Examples 6 to 11 are given in the table. MSA stands for maleic anhydride. The molar data relate to 100 g of copolymer.

Example 11

To the favorable influence of the fuels of the invention on the Showing corrosion behavior of gasoline engines is unleaded, not additive super petrol (SOK) (product of the oil refinery Mannheim) a corrosion test according to DIN 51 585 or ASTM D 665-60 or IP 135/64 at a temperature of 23 ° C and a test time of 5 h subject, the fuel additives according to the invention from the Examples 6 to 10 each of the fuel in amounts of 300 ppm by weight be added. In the fuels of the invention Steel fingers found no corrosion. In contrast, the will not additized fuel the degree of corrosion 3 determined.

Example 12

According to the engine test on an Opel Kadett engine CEC F-02-C-79 with a fuel according to Example 11, which is an addition of Contains 300 ppm by weight of the potassium compound according to Example 6, the Valve deposits averaging 327 mg / inlet valve 204 mg / inlet decreased. This makes the usual additive requirement for protection and significantly reduced to keep the intake systems clean.

Claims (5)

1. Fuels for gasoline engines containing small amounts of copolymers from olefins with 2 to 40 carbon atoms and maleic anhydride and / or Cycloolefins and maleic anhydride with a total molecular weight of 500 to 20,000 g per mole, the carboxyl groups of the copolymers partially with alkali or alkaline earth to form the Alkali metal or alkaline earth metal salts are implemented and the rest the carboxyl groups with alcohols and / or amines with up to 50 carbon atoms to the corresponding ester and / or amide groups and / or Ammonium salts is implemented. 2. Fuels according to claim 1, characterized by a content of the Copolymers from 10 to 2000 ppm by weight. 3. Fuels according to claim 1 and 2, characterized in that the Copolymers contain at least 3% by weight of alkali or alkaline earth exhibit. 4. Fuels according to claim 1 to 3, characterized in that the Carboxyl groups of the copolymers to form the alkali metal salts are neutralized. 5. Fuels according to claim 1 to 4, characterized in that the Carboxyl groups of the copolymers to form the potassium salts are neutralized.